IF ISNULL (ATTR([Plant Code],[Material ID]),STR([Export Create Date]))
Your ISNULL is to Return TRUE or FALSE, I think You need to rewrite this.
What are you trying to accomplish with this:
ISNULL (ATTR([Plant Code],[Material ID]),STR([Export Create Date]))
The ATTR() function can't encompass more than one field.
Apologies as I'm still fairly new to Tableau. I have multiple values for each given month & I would like to filter out the duplicate values while selecting the latest/last value for each month.
Please attach a workbook to help you.